The 17 Again star took in a performance last night of Broadway's newest hit Rock of Ages. It's no Showboat, but it is a production with plenty of song and dance.

The show stars American Idol alum Constantine Maroulis as a wannabe rocker in 1987 Los Angeles and features the music of Journey, Styx, REO Speedwagon, Pat Benatar and Twisted Sister...

Efron attended the musical with his father and younger brother after a day of promoting and doing press for 17 Again. (He did Letterman and introduced a screening of the movie hosted by Seventeen magazine, natch, among other things.)

"He was very, very nice," a fellow theatergoer tells me. "He went backstage and everyone wanted a picture with him."

Maroulis even joked that Efron will probably play his part if the show ever becomes a movie.

We don't think Zac would have any problem growing out his own locks for the perfect hair-band 'do. Have ya seen the new cover of GQ?